U.S. patent application number 11/214711 was filed with the patent office on 2006-05-11 for thin film magnetic head, head gimbal assembly, and hard disk drive.
This patent application is currently assigned to TDK Corporation. Invention is credited to Nozomu Hachisuka, Noriaki Kasahara.
Application Number | 20060098349 11/214711 |
Document ID | / |
Family ID | 36316055 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060098349 |
Kind Code |
A1 |
Kasahara; Noriaki ; et
al. |
May 11, 2006 |
Thin film magnetic head, head gimbal assembly, and hard disk
drive
Abstract
In a thin film magnetic head of the present invention, lead
formation patterns of a first lead for connection between a lower
shield layer and a first extraction electrode portion and a second
lead for connection between an upper shield layer and a second
extraction electrode portion are each formed so as not to have an
overlapping portion with a heatsink layer but to bypass the
heatsink layer when observing from the upper shield layer side
toward the lower shield layer in a transparent state in plan view.
Therefore, it is possible to increase an effect of heat radiation
to the substrate side on the basis of the presence of the heatsink
layer to thereby limit propagation of heat to a magnetoresistive
effect layer as much as possible and further to achieve a drastic
improvement in recording and reproducing characteristics at high
recording frequencies, i.e. frequency characteristics (f
characteristics) in a high frequency region.
Inventors: |
Kasahara; Noriaki; (Tokyo,
JP) ; Hachisuka; Nozomu; (Tokyo, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
TDK Corporation
Tokyo
JP
|
Family ID: |
36316055 |
Appl. No.: |
11/214711 |
Filed: |
August 31, 2005 |
Current U.S.
Class: |
360/317 ;
G9B/5.077; G9B/5.151 |
Current CPC
Class: |
G11B 5/31 20130101; G11B
5/4826 20130101 |
Class at
Publication: |
360/317 |
International
Class: |
G11B 5/33 20060101
G11B005/33; G11B 5/127 20060101 G11B005/127 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 8, 2004 |
JP |
2004-323197 |
Claims
1. A thin film magnetic head comprising: a substrate; a lower
shield layer formed on said substrate; an upper shield layer formed
on said lower shield layer; a read magnetic head element of a CPP
(Current Perpendicular to Plane) structure interposed between said
lower shield layer and said upper shield layer; a heatsink layer
formed at a rearward portion (in a direction away from an ABS
serving as a recording/reproduction-side surface) of said lower
shield layer and said upper shield layer; a first extraction
electrode portion and a second extraction electrode portion formed
at a further rearward portion (in the direction away from the ABS
serving as the recording/reproduction-side surface) of said
heatsink layer; a first lead for connection between said lower
shield layer and said first extraction electrode portion; and a
second lead for connection between said upper shield layer and said
second extraction electrode portion, wherein, when observing from
said upper shield layer side toward said lower shield layer in a
transparent state in plan view, formation patterns of said first
lead and said second lead are each formed so as not to have an
overlapping portion with said heatsink layer but to bypass said
heatsink layer.
2. The thin film magnetic head according to claim 1, wherein said
heatsink layer has a stack structure comprising a lower heatsink
portion having the same composition as said lower shield layer and
an upper heatsink portion having the same composition as said upper
shield layer, and said lower heatsink portion and said upper
heatsink portion are formed so as to be separated from said lower
shield layer and said upper shield layer.
3. The thin film magnetic head according to claim 1, wherein said
first lead connects between an exposed connecting portion of said
lower shield layer and said first extraction electrode portion to
thereby achieve electrical conduction between said lower shield
layer and said first extraction electrode portion, and wherein said
second lead connects between a connecting portion on an insulating
layer formed on said lower shield layer and said second extraction
electrode portion and then said upper shield layer is formed so
that a connecting portion of said second lead located at the
connecting portion on said insulating layer is connected to said
upper shield layer, thereby achieving electrical conduction between
said upper shield layer and said second extraction electrode
portion.
4. The thin film magnetic head according to claim 1, wherein said
first extraction electrode portion has a stack structure comprising
a first lower electrode layer portion having the same composition
as said lower shield layer and a first upper electrode layer
portion having the same composition as said upper shield layer and
is formed so as to be separated from said heatsink layer, and
wherein said second extraction electrode portion has a stack
structure comprising a second lower electrode layer portion having
the same composition as said lower shield layer and a second upper
electrode layer portion having the same composition as said upper
shield layer and is formed so as to be separated from said heatsink
layer.
5. The thin film magnetic head according to claim 1, wherein said
read magnetic head element of the CPP structure is a CPP-GMR (Giant
MagnetoResistive) element or a CPP-TMR (Tunnel MagnetoResistive)
element.
6. The thin film magnetic head according to claim 1, wherein said
lower shield layer and said upper shield layer have a function of
shielding magnetism from the exterior and further have a function
as electrodes for causing a current to flow through said read
magnetic head element of the CPP structure.
7. A head gimbal assembly comprising: a slider including a thin
film magnetic head and disposed so as to confront a recording
medium; and a suspension elastically supporting said slider,
wherein said thin film magnetic head comprises: a substrate; a
lower shield layer formed on said substrate; an upper shield layer
formed on said lower shield layer; a read magnetic head element of
a CPP (Current Perpendicular to Plane) structure interposed between
said lower shield layer and said upper shield layer; a heatsink
layer formed at a rearward portion (in a direction away from an ABS
serving as a recording/reproduction-side surface) of said lower
shield layer and said upper shield layer; a first extraction
electrode portion and a second extraction electrode portion formed
at a further rearward portion (in the direction away from the ABS
serving as the recording/reproduction-side surface) of said
heatsink layer; a first lead for connection between said lower
shield layer and said first extraction electrode portion; and a
second lead for connection between said upper shield layer and said
second extraction electrode portion, and wherein, when observing
from said upper shield layer side toward said lower shield layer in
a transparent state in plan view, formation patterns of said first
lead and said second lead are each formed so as not to have an
overlapping portion with said heatsink layer but to bypass said
heatsink layer.
8. A hard disk drive comprising: a slider including a thin film
magnetic head and disposed so as to confront a disc-shaped
recording medium driven to be rotated; and a positioning device
supporting said slider and positioning said slider relative to said
recording medium, wherein said thin film magnetic head comprises: a
substrate; a lower shield layer formed on said substrate; an upper
shield layer formed on said lower shield layer; a read magnetic
head element of a CPP (Current Perpendicular to Plane) structure
interposed between said lower shield layer and said upper shield
layer; a heatsink layer formed at a rearward portion (in a
direction away from an ABS serving as a recording/reproduction-side
surface) of said lower shield layer and said upper shield layer; a
first extraction electrode portion and a second extraction
electrode portion formed at a further rearward portion (in the
direction away from the ABS serving as the
recording/reproduction-side surface) of said heatsink layer; a
first lead for connection between said lower shield layer and said
first extraction electrode portion; and a second lead for
connection between said upper shield layer and said second
extraction electrode portion, and wherein, when observing from said
upper shield layer side toward said lower shield layer in a
transparent state in plan view, formation patterns of said first
lead and said second lead are each formed so as not to have an
overlapping portion with said heatsink layer but to bypass said
heatsink layer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a thin film magnetic head
comprising a read magnetic head element of a CPP structure for
reading as a signal a magnetic field strength recorded on a
magnetic recording medium or the like, and further relates to a
head gimbal assembly and a hard disk drive each including such a
thin film magnetic head.
[0003] 2. Description of the Related Art
[0004] In recent years, following the improvement in a real
recording density of hard disk drives, improvement in performance
of thin film magnetic heads has been required. As the thin film
magnetic heads, use has been widely made of composite thin film
magnetic heads each having a structure wherein a reproducing head
comprising a read magnetic head element dedicated for reading and a
recording head comprising an induction-type electromagnetic
transducer element dedicated for writing are stacked in layers on a
substrate.
[0005] The read magnetic head elements can be roughly classified
into two types depending on in which direction a current (sense
current) for detection of a magnetic field flows with respect to an
element stacking direction of the stacked element structure.
[0006] Specifically, they are roughly classified into a CIP
(Current In Plane) element in which the current flows along the
stacked layer planes of the stacked element structure and a CPP
(Current Perpendicular to Plane) element in which the current flows
in the stacking direction (perpendicular direction) of the stacked
element structure.
[0007] A CIP-GMR (Giant MagnetoResistive) element can be cited as
the former element, while, a CPP-GMR element or a CPP-TMR (Tunnel
MagnetoResistive) element can be cited as the latter element.
[0008] Particularly, the magnetic head having the latter CPP read
magnetic head element is a head aimed at by the present invention
and has a structure in which upper and lower surfaces of the
element are sandwiched between a lower shield layer and an upper
shield layer. Normally, the lower shield layer and the upper shield
layer also function as electrodes, wherein a voltage is applied
across the lower shield layer and the upper shield layer so that a
sense current flows in the stacking direction (perpendicular
direction) of the element.
[0009] Presently, as a structure generally used for a magnetic
head, there is employed a shield shape in which upper and lower
shield layers shielding a read magnetic head element each have a
length in an MR height direction (an inward depth direction
perpendicular to an ABS (Air Bearing Surface)) which is shorter
than a width thereof. This is because magnetic domains of the
shield layer are made stable by setting the shape of the shield
layer laterally long, thereby preventing occurrence of noise which
is otherwise caused by coupling between domain wall movement of the
shield layer and a free layer due to magnetic flux from a magnetic
recording medium at the time of a read (reproduction)
operation.
[0010] On the other hand, in the magnetic head structure, for
example, at the time of signal writing, there is generation of
Joule heat from a coil layer in an induction-type electromagnetic
transducer element and heat caused by eddy current loss from upper
and lower magnetic layers and thus there may occur a so-called TPTP
(Thermal Pole Tip Protrusion) phenomenon in which an overcoat layer
covering the whole element is heat expanded due to such generated
heat so that the magnetic head element protrudes toward the surface
of a magnetic disk. When the shield layers each having the short
length in the MR height direction are employed as described above,
the area of about half the coil layer is a region where no shield
material exists thereunder so that the influence of the TPTP
phenomenon significantly appears. By disposing a heatsink under the
coil layer, it becomes possible to release the heat to the AlTiC
side to thereby suppress the TPTP phenomenon. However, it is
necessary to limit the propagation of the heat to the
magnetoresistive effect layer (element) as much as possible to
thereby keep the signal reading capability.
[0011] Further, with respect to a yearly increasing demand for
higher recording densities in magnetic heads, there is required a
drastic improvement in recording and reproducing characteristics at
high recording frequencies, i.e. frequency characteristics (f
characteristics) in a high frequency region.
[0012] The present invention has been conceived under these
circumstances and has an object to provide a thin film magnetic
head that can limit the propagation of heat to a magnetoresistive
effect layer as much as possible by increasing an effect of heat
radiation to the substrate side and, further, that can achieve a
drastic improvement in recording and reproducing characteristics at
high recording frequencies, i.e. frequency characteristics (f
characteristics) in a high frequency region, and to further provide
a head gimbal assembly and a hard disk drive each comprising such
an improved thin film magnetic head.
SUMMARY OF THE INVENTION
[0013] For accomplishing the foregoing object, according to one
aspect of the present invention, there is obtained a thin film
magnetic head comprising a substrate; a lower shield layer formed
on the substrate; an upper shield layer formed on the lower shield
layer; a read magnetic head element of a CPP (Current Perpendicular
to Plane) structure interposed between the lower shield layer and
the upper shield layer; a heatsink layer formed at a rearward
portion (in a direction away from an ABS serving as a
recording/reproduction-side surface) of the lower shield layer and
the upper shield layer; a first extraction electrode portion and a
second extraction electrode portion formed at a further rearward
portion (in the direction away from the ABS serving as the
recording/reproduction-side surface) of the heatsink layer; a first
lead for connection between the lower shield layer and the first
extraction electrode portion; and a second lead for connection
between the upper shield layer and the second extraction electrode
portion, wherein, when observing from the upper shield layer side
toward the lower shield layer in a transparent state in plan view,
formation patterns of the first lead and the second lead are each
formed so as not to have an overlapping portion with the heatsink
layer but to bypass the heatsink layer.
[0014] As a preferred mode of the present invention, it is
configured such that the heatsink layer has a stack structure
comprising a lower heatsink portion having the same composition as
the lower shield layer and an upper heatsink portion having the
same composition as the upper shield layer, and the lower heatsink
portion and the upper heatsink portion are formed so as to be
separated from the lower shield layer and the upper shield
layer.
[0015] As a preferred mode of the present invention, it is
configured such that the first lead connects between an exposed
connecting portion of the lower shield layer and the first
extraction electrode portion to thereby achieve electrical
conduction between the lower shield layer and the first extraction
electrode portion and that the second lead connects between a
connecting portion on an insulating layer formed on the lower
shield layer and the second extraction electrode portion and then
the upper shield layer is formed so that a connecting portion of
the second lead located at the connecting portion on the insulating
layer is connected to the upper shield layer, thereby achieving
electrical conduction between the upper shield layer and the second
extraction electrode portion.
[0016] As a preferred mode of the present invention, it is
configured such that the first extraction electrode portion has a
stack structure comprising a first lower electrode layer portion
having the same composition as the lower shield layer and a first
upper electrode layer portion having the same composition as the
upper shield layer and is formed so as to be separated from the
heatsink layer and that the second extraction electrode portion has
a stack structure comprising a second lower electrode layer portion
having the same composition as the lower shield layer and a second
upper electrode layer portion having the same composition as the
upper shield layer and is formed so as to be separated from the
heatsink layer.
[0017] As a preferred mode of the present invention, it is
configured such that the read magnetic head element of the CPP
structure is a CPP-GMR (Giant MagnetoResistive) element or a
CPP-TMR (Tunnel MagnetoResistive) element.
[0018] As a preferred mode of the present invention, it is
configured such that the lower shield layer and the upper shield
layer have a function of shielding magnetism from the exterior and
further have a function as electrodes for causing a current to flow
through the read magnetic head element of the CPP structure.
[0019] According to another aspect of the present invention, there
is obtained a head gimbal assembly comprising a slider including
the foregoing thin film magnetic head and disposed so as to
confront a recording medium, and a suspension elastically
supporting the slider.
[0020] According to another aspect of the present invention, there
is obtained a hard disk drive comprising a slider including the
foregoing thin film magnetic head and disposed so as to confront a
disc-shaped recording medium driven to be rotated, and a
positioning device supporting the slider and positioning the slider
relative to the recording medium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a diagram for explaining a schematic structure of
a thin film magnetic head according to a preferred embodiment of
the present invention, which shows a section of the thin film
magnetic head perpendicular to an ABS (Air Bearing Surface) and a
substrate;
[0022] FIG. 2 is a diagram, as seen from the ABS side of the thin
film magnetic head, for explaining a structure of the thin film
magnetic head according to the preferred embodiment of the present
invention;
[0023] FIG. 3 is a perspective view showing a slider included in a
head gimbal assembly in an embodiment of the present invention;
[0024] FIG. 4 is a perspective view showing a head arm assembly
including the head gimbal assembly in the embodiment of the present
invention;
[0025] FIG. 5 is an explanatory diagram showing the main part of a
hard disk drive in the embodiment of the present invention;
[0026] FIG. 6 is a plan view of the hard disk drive in the
embodiment of the present invention;
[0027] FIG. 7 is a graph showing recording/reproducing
characteristics (frequency characteristics) with respect to an
example sample and a comparative example sample;
[0028] FIG. 8, (A) is a plan view for explaining processes of
manufacturing a main part structure of a thin film magnetic head of
the present invention, while FIG. 8, (B) and FIG. 8, (C) are
schematic sectional views in predetermined directions of FIG. 8,
(A), respectively;
[0029] FIG. 9, (A) is a plan view for explaining the processes of
manufacturing the main part structure of the thin film magnetic
head of the present invention, while FIG. 9, (B) and FIG. 9, (C)
are schematic sectional views in the predetermined directions of
FIG. 9, (A), respectively;
[0030] FIG. 10, (A) is a plan view for explaining the processes of
manufacturing the main part structure of the thin film magnetic
head of the present invention, while FIG. 10, (B) and FIG. 10, (C)
are schematic sectional views in the predetermined directions of
FIG. 10, (A), respectively;
[0031] FIG. 11, (A) is a plan view for explaining the processes of
manufacturing the main part structure of the thin film magnetic
head of the present invention, while FIG. 11, (B) and FIG. 11, (C)
are schematic sectional views in the predetermined directions of
FIG. 11, (A), respectively;
[0032] FIG. 12, (A) is a plan view for explaining the processes of
manufacturing the main part structure of the thin film magnetic
head of the present invention, while FIG. 12, (B) and FIG. 12, (C)
are schematic sectional views in the predetermined directions of
FIG. 12, (A), respectively;
[0033] FIG. 13, (A) is a plan view for explaining the processes of
manufacturing the main part structure of the thin film magnetic
head of the present invention, while FIG. 13, (B) and FIG. 13, (C)
are schematic sectional views in the predetermined directions of
FIG. 13, (A), respectively;
[0034] FIG. 14, (A) is a plan view for explaining the processes of
manufacturing the main part structure of the thin film magnetic
head of the present invention, while FIG. 14, (B) and FIG. 14, (C)
are schematic sectional views in the predetermined directions of
FIG. 14, (A), respectively;
[0035] FIG. 15, (A) is a plan view for explaining the processes of
manufacturing the main part structure of the thin film magnetic
head of the present invention, while FIG. 15, (B) and FIG. 15, (C)
are schematic sectional views in the predetermined directions of
FIG. 15, (A), respectively;
[0036] FIG. 16, (A) is a plan view for explaining the processes of
manufacturing the main part structure of the thin film magnetic
head of the present invention, while FIG. 16, (B) and FIG. 16, (C)
are schematic sectional views in the predetermined directions of
FIG. 16, (A), respectively;
[0037] FIG. 17, (A) is a plan view for explaining the processes of
manufacturing the main part structure of the thin film magnetic
head of the present invention, while FIG. 17, (B) and FIG. 17, (C)
are schematic sectional views in the predetermined directions of
FIG. 17, (A), respectively; and
[0038] FIG. 18 is a plan view to be compared with FIG. 17, (A),
wherein, when drawing leads, the leads are disposed linearly
between extraction electrode portions and connecting portions
(contact holes) of shield layers, respectively, so that each of the
leads has the shortest length, and therefore the leads are each
formed so as to have an overlapping portion with a heatsink layer
in a perpendicular fashion.
DETAILED DESCRIPTION OF THE INVENTION
[0039] Now, the best mode for carrying out the present invention
will be described in detail hereinbelow with reference to the
accompanying drawings.
[0040] FIG. 1 is a diagram for explaining a schematic structure of
a thin film magnetic head according to a preferred embodiment of
the present invention, which schematically shows a section of the
thin film magnetic head perpendicular to an ABS (Air Bearing
Surface) facing a magnetic recording medium and to a substrate.
FIG. 2 is a diagram, as seen from the ABS side of the thin film
magnetic head, for explaining a structure of the thin film magnetic
head according to the preferred embodiment of the present
invention.
[0041] As shown in these figures, a thin film magnetic head 1 of
the present invention comprises a substrate 2 (normally, a
so-called slider substrate), an underfilm 3 normally formed on the
substrate 2, a lower shield layer 5 formed on the underfilm 3, and
an upper shield layer 12 formed on the lower shield layer 5 and,
between the lower shield layer 5 and the upper shield layer 12, a
read magnetic head element 7 of a CPP (Current Perpendicular to
Plane) structure is interposed.
[0042] The lower shield layer 5 and the upper shield layer 12 are
formed so as to mainly exhibit a function as electrodes for causing
a sense current to flow in the stacking direction with respect to
the read magnetic head element 7 of the CPP structure and a
function of magnetic shielding with respect to the read magnetic
head element 7.
[0043] Further, over the upper shield layer 12 is formed a lower
magnetic pole layer 14 for a write magnetic head element, i.e. for
constituting an induction-type electromagnetic transducer element
dedicated for writing. In combination with an upper magnetic pole
layer (symbols 21, 33, etc.) including a pole 21, the lower
magnetic pole layer 14 forms a substantially closed magnetic
circuit for writing via a gap layer 18 interposed therebetween.
Normally, this lower magnetic pole layer 14 also exhibits a
magnetic shielding function.
[0044] There is no particular limitation to the number of thin film
coil layers for magnetic induction of the write magnetic head
element but, normally, a two-layer stacked coil structure 26, 30 is
employed. The two-layer stacked coil structure will be easily
understood by a time-domain explanation of manufacturing processes
which will be given later.
[0045] As shown in FIG. 1, during a write or read operation, the
thin film magnetic head 1 is flying over the surface of a rotating
magnetic disk 262 hydrodynamically with a predetermined gap
therebetween.
[0046] Further, between the lower shield layer 5 and the read
magnetic head element 7 and between the read magnetic head element
7 and the upper shield layer 12, a gap layer made of Ta or the like
is normally formed. In FIG. 1, symbol 77 denotes an overcoat.
[0047] The thin film magnetic head 1 of the present invention
comprises a heatsink layer 40 for releasing heat generated in the
head to the substrate 2 side. The heatsink layer 40 is formed at a
rearward portion (in a direction away from the ABS serving as a
recording/reproduction-side surface) of the lower shield layer 5,
the upper shield layer 12, and the lower magnetic pole layer 14.
The heatsink layer 40 has a stack structure comprising a lower
heatsink portion 41 having the same composition as the lower shield
layer 5 and an upper heatsink portion 45 having the same
composition as the upper shield layer 12. Further, the lower
heatsink portion 41 and the upper heatsink portion 45 are formed so
as to be separated from the lower shield layer 5 and the upper
shield layer 12 via an insulating layer interposed therebetween.
This insulating layer is preferably made of a material having a low
thermal conductivity, such as alumina or silicon oxide.
[0048] It is desirable that the lower heatsink portion 41 and the
upper heatsink portion 45 be formed simultaneously with the
formation of the lower shield layer 5 and the upper shield layer
12, respectively. This is for forming the heatsink layer 40
efficiently and economically.
[0049] The most characteristic main part of the thin film magnetic
head 1 of the present invention is not shown in FIG. 1 because its
definite overall structure cannot be sufficiently described in the
sectional view of FIG. 1.
[0050] To give an outline of the main part in advance by the use of
only a sentence (for details, see later description about
manufacturing processes for the main part structure shown in FIGS.
8 to 17), a first extraction electrode portion 50 and a second
extraction electrode portion 60 are formed at a further rearward
portion (in the direction away from the ABS serving as the
recording/reproduction-side surface) of the heatsink layer 40, and
the lower shield layer 5 and the first extraction electrode portion
50 are connected together by a first lead 71 while the upper shield
layer 12 and the second extraction electrode portion 60 are
connected together by a second lead 75.
[0051] Further, when observing from the upper shield layer 12 side
toward the lower shield layer 5 in a transparent state in plan
view, formation patterns of those leads are each formed so as not
to have an overlapping portion with the heatsink layer 40 but to
bypass the heatsink layer 40.
[0052] In order to enable easy and definite understanding of such a
main part structure of the present invention, the manufacturing
processes for the main part structure will be described
hereinbelow.
[0053] Processes of Manufacturing Main Part Structure of Thin Film
Magnetic Head of the Present Invention
[0054] Referring to FIGS. 8 to 17, the processes of manufacturing
the main part structure of the thin film magnetic head of the
present invention will be described in sequence.
[0055] In each of the figures, a diagram shown at (A) in the upper
part of the drawing sheet is a plan view schematically showing a
device itself, a diagram shown at (B) in the middle part of the
drawing sheet is a schematic sectional view taken along line
.alpha.-.alpha.' in the plan view shown at (A), and a diagram shown
at (C) in the lower part of the drawing sheet is a schematic
sectional view taken along line .beta.-.beta.' in the plan view
shown at (A).
[0056] Note that the scales of the diagram shown at (B) and the
diagram shown at (C) are not the same.
[0057] (1) Formation of Lower Shield (Electrode) Layer
[0058] As shown in FIG. 8, (A) to (C), for example, an
Al.sub.2O.sub.3 underfilm is formed on a slider substrate made of
an AlTiC material and, on this underfilm, a predetermined pattern
made of a material of a lower shield (electrode) layer is
formed.
[0059] Specifically, as shown in FIG. 8, (A) to (C), an electrode
underfilm for plating is formed over the whole surface, then a
lower shield layer 5, a lower heatsink portion 41, a first lower
electrode layer portion 51, and a second lower electrode layer
portion 61 of a magnetic head are formed according to a photoresist
technique and, after performing plating and stripping a resist, the
electrode underfilm is removed. Thereafter, an Al.sub.2O.sub.3
insulating film is formed and then a CMP treatment is carried
out.
[0060] Through the foregoing processing, as shown in FIG. 8, (A),
the lower shield layer 5, the lower heatsink portion 41, the first
lower electrode layer portion 51, and the second lower electrode
layer portion 61 of the magnetic head are formed of the same
material in the state where they are separated from each other by
the insulating film 4. Note that, in the sectional views of FIG. 8,
(B) and (C), illustration of the substrate and the underfilm is
omitted (the same shall apply to the corresponding (B) and (C)
diagrams hereinafter).
[0061] (2) Formation of CPP-Structure Read Magnetic Head Element
Film
[0062] As shown in FIG. 9, (A) to (C), a gap layer 6 is formed and
then, for example, a TMR film 7 being a CPP-structure read magnetic
head element film is formed over the whole surface (see
particularly FIG. 9, (B) and (C)). Although the TMR film normally
has a multilayer film structure, it is simplified as a single-layer
film herein.
[0063] (3) Formation of Connecting Portion
[0064] As shown in FIG. 10, (A) to (C), by performing a
predetermined pattern photoresist technique and carrying out
milling to strip a resist, a corner portion 5a (exposed connecting
portion 5a) of the lower shield layer 5, the first lower electrode
layer portion 51, and the second lower electrode layer portion 61
of the magnetic head are exposed, respectively, as particularly
shown in FIG. 10, (A).
[0065] (4) Photoresist Formation for Track Width Formation
[0066] As shown in FIG. 11, (A) to (C), a predetermined pattern
photoresist technique is performed to thereby form a photoresist R1
of a predetermined pattern so as to define a track width Tw of the
TMR element (formation of a mask pattern).
[0067] (5) Track Width Formation
[0068] As shown in FIG. 12, (A) to (C), portions of the TMR film 7
partly exposed to define the track width Tw of the TMR element (see
FIG. 11, (A)) are milled, then an insulating film 8 and a hard
magnetic film 9 (a bias applying layer for the TMR element) are
formed in order at the milled portions, and then lift-off is
performed. After the lift-off, the corner portion 5a (exposed
connecting portion 5a) of the lower shield layer 5, the first lower
electrode layer portion 51, and the second lower electrode layer
portion 61 are in the state where they are exposed,
respectively.
[0069] (6) Photoresist Formation for MR Height Formation
[0070] As shown in FIG. 13, (A) to (C), a photoresist R2 of a
predetermined pattern is formed so as to define a so-called MR
height of the TMR element, while, a photoresist R3 is formed on the
corner portion 5a of the lower shield layer 5 and photoresists R4
are formed on the first lower electrode layer portion 51 and the
second lower electrode layer portion 61 (formation of a mask
pattern).
[0071] (7) MR Height Formation
[0072] As shown in FIG. 14, (A) to (C), milling is carried out
(portions other than the mask in FIG. 13, (A) are milled) so as to
define the so-called MR height of the TMR element, thereby leaving
the TMR film 7 only at the portion necessary for the element, and
thereafter, an insulating film 10 of alumina or the like is formed
at the milled portions-and then lift-off is performed.
[0073] After the lift-off, as shown in FIG. 14, (A), the corner
portion 5a (exposed connecting portion 5a) of the lower shield
layer 5, the first lower electrode layer portion 51, and the second
lower electrode layer portion 61 are in the state where they are
exposed, respectively.
[0074] (8) Lead Formation
[0075] As shown in FIG. 15, (A) to (C), a photoresist of a
predetermined pattern is formed so as to enable formation of a
first lead 71 and a second lead 75 (formation of a mask pattern is
not shown), then the first lead 71 and the second lead 75 are
formed, and then lift-off is performed (the state of FIG. 15,
(A)).
[0076] When forming the first lead 71 and the second lead 75, it is
important that when observing from the upper shield layer 12 side
toward the lower shield layer 5 in a transparent state in plan view
(corresponding to the state where FIG. 15, (A) is seen from above
in a direction perpendicular to the drawing sheet), formation
patterns of those leads each be formed so as not to have an
overlapping portion with the heatsink layer 40 but to bypass the
heatsink layer 40. If "a transparent state in plan view" is defined
by another expression, it may be a state where transmission
observation is performed in the element stacking direction from the
stacked layer plane of the element.
[0077] It is desirable that the bypass length be as short as
possible while avoiding occurrence of an overlapping portion with
the heatsink layer 40.
[0078] In the state after the lift-off as shown in FIG. 15, (A),
the first lead 71 connects between the exposed connecting portion
5a of the lower shield layer 5 (see particularly FIG. 14, (A)) and
the first lower electrode layer portion 51 (see particularly FIG.
14, (A)). With this configuration, there is achieved electrical
conduction between the lower shield layer 5 and the first lower
electrode layer portion 51 (a component of the first extraction
electrode portion 50).
[0079] The first lower electrode layer portion 51 is one of
components of the first extraction electrode portion 50.
[0080] Further, in the state after the lift-off, the second lead 75
connects between a connecting portion 10a of the insulating layer
10 (see particularly FIG. 14, (A)) formed on the lower shield layer
5 and the second lower electrode layer portion 61. Because of the
presence of the interposed insulating layer 10 (10a), the second
lead 75 is insulated from the lower shield layer 5. The second
lower electrode layer portion 61 is one of components of the second
extraction electrode portion 60.
[0081] (9) Formation of Lead Connecting Portion
[0082] As shown in FIG. 16, (A) to (C), a photoresist is formed
(formation of a mask pattern) so that a portion 71a of the first
lead 71 corresponding to an overlapping position with the first
lower electrode layer portion 51, a portion 75a of the second lead
75 corresponding to an overlapping position with the second lower
electrode layer portion 61, and a portion 75b of the second lead 75
corresponding to an overlapping position with the connecting
portion 10a of the insulating layer 10 are respectively exposed
after the lift-off.
[0083] Thereafter, an insulating film 11 of, for example, SiO.sub.2
is formed on other portions of the first lead 71 and the second
lead 75 which should be insulated, and then lift-off is performed
(the state of FIG. 16, (A)).
[0084] In the state after the lift-off as shown in FIG. 16, (A),
the portion 71a of the first lead 71 located at the first lower
electrode layer portion 51 is in an exposed state because there is
no insulating film 11. Likewise, the portion 75a of the second lead
75 located at the second lower electrode layer portion 61 is in an
exposed state because there is no insulating film 11. Further, the
portion 75b of the second lead 75 corresponding to the overlapping
position with the connecting portion 10a is also in an exposed
state because there is no insulating film 11.
[0085] (10) Formation of Upper Shield (Electrode) Layer
[0086] As shown in FIG. 17, (A) to (C), a photoresist technique is
carried out so that the upper shield layer 12, an upper heatsink
portion 45, a first upper electrode layer portion 55, and a second
upper electrode layer portion 65 of the magnetic head are formed of
a material of the upper shield layer (a pattern shown in FIG. 17,
(A)).
[0087] By forming the upper shield layer 12 in the pattern shown in
FIG. 17, (A), the exposed connecting portion 75a of the second lead
75 is connected to the upper shield layer 12 so that there is
achieved electrical conduction between the upper shield layer 12
and the second lower electrode layer portion 61. The first upper
electrode layer portion 55 is one of the components of the first
extraction electrode portion 50. The second upper electrode layer
portion 65 is one of the components of the second extraction
electrode portion 60.
[0088] As described above, in the manufacturing processes for the
main part structure of the thin film magnetic head on the basis of
FIGS. 8 to 17, the gist of the present invention resides in that
when forming the first lead 71 and the second lead 75, the lead
formation patterns thereof are each formed so as not to have an
overlapping portion with the heatsink layer 40 but to bypass the
heatsink layer 40 in the case of observing from the upper shield
layer 12 side toward the lower shield layer 5 in the transparent
state in plan view. As described above, the bypass distance is
preferably as short as possible.
[0089] When drawing a lead, everybody may think to connect between
an extraction electrode portion and a contact hole (connecting
portion) of a shield layer with the shortest linear lead. This is
for making the lead length as short as possible to reduce a
resistance value due to the lead as much as possible, thereby
making a primary resistance change of a magnetoresistive effect
element distinguished as much as possible.
[0090] In such a case, in the head structure where a heatsink is
provided between the extraction electrode portion and the shield
layer, the lead is sandwiched by the heatsink.
[0091] However, as a result of assiduous researches conducted by
the present inventors on the lead drawing manner in the structure
where the heatsink is disposed between the extraction electrode
portion and the shield layer, they have reached a conclusion that
setting of a lead drawing manner is required under a new concept,
and have conceived the present invention.
[0092] That is, with respect to a demand for higher recording
densities in magnetic heads, stable recording and reproducing
characteristics at high recording frequencies (frequency
characteristics: hereinafter referred to simply as "f
characteristics") are required. Generally, since a reproducing head
is constituted by a parallel circuit of a resistance (R) and a
capacitance (C), it can be regarded as an RC low-pass filter
circuit. In this case, a cutoff frequency (fc) is given by the
following formula (1): fc=1/2.pi.RC [Hz] (1)
[0093] The cutoff frequency is a frequency at which the output of
the circuit becomes 1/ {square root over (2)} with respect to an
output at f=0.
[0094] Herein, the present inventors have considered that a
resistance value of a reproducing head is set to a predetermined
value depending on a specification per head and, in order to
achieve a drastic improvement in frequency characteristics (f
characteristics) in a high frequency region (GHz level), even if
there occurs a disadvantage of slight increase (about 1%) in
resistance based on a slight increase in length of a lead drawing
pattern, an advantage derived from a collateral reduction in
capacitance (C) is quite larger.
[0095] That is, the present inventors have considered that the
capacitance (C) is the most important factor that can extend the
frequency where the constant output can be maintained, to a higher
frequency region side. The effect thereof will be seen by referring
to test results of a later-described example.
[0096] Referring back to the description of the structure of the
magnetic head element, as the CPP-structure read magnetic head
element used in the present invention, there is cited a CPP-GMR
(Giant MagnetoResistive) element or a CPP-TMR (Tunnel
MagnetoResistive) element.
[0097] As the substrate 2 in the present invention, use is made of,
for example, AlTiC (Al.sub.2O.sub.3--TiC).
[0098] The lower shield layer 5 and the upper shield layer 12 in
the present invention are each made of, for example, FeAlSi, NiFe,
CoFe, CoFeNi, FeN, FeZrN, FeTaN, CoZrNb, or CoZrTa. Each of them is
formed by the sputtering method, the plating method, or the like
and the thickness thereof is set to about 1.5 to 3.0 m. The lower
magnetic pole layer 14 in the present invention is made of, for
example, FeAlSi, NiFe, CoFe, CoFeNi, FeN, FeZrN, FeTaN, CoZrNb, or
CoZrTa. It is formed by the sputtering method, the plating method,
or the like and the thickness thereof is set to about 1.5 to 5.0
.mu.m.
[0099] Head Gimbal Assembly and Hard Disk Drive
[0100] Hereinbelow, description will be made of a head gimbal
assembly and a hard disk drive according to an embodiment of the
present invention.
[0101] Referring first to FIG. 3, a slider 210 included in the head
gimbal assembly will be described. In the hard disk drive, the
slider 210 is disposed so as to confront a hard disk serving as a
disc-shaped recording medium and driven to be rotated. The slider
210 comprises a base body 211 mainly composed of the substrate 2
and the overcoat 77 in FIG. 1.
[0102] The base body 211 has a generally hexahedral shape. One
surface, among six surfaces, of the base body 211 is arranged to
confront the hard disk. This one surface is formed with the
ABS.
[0103] When the hard disk is rotated in a z-direction in FIG. 3,
lift is generated below the slider 210 in a y-direction in FIG. 3
because of an air flow passing between the hard disk and the slider
210. This lift causes the slider 210 to rise from the surface of
the hard disk. Incidentally, an x-direction in FIG. 3 represents a
track traverse direction of the hard disk.
[0104] The thin film magnetic head 1 according to this embodiment
is formed in the neighborhood of an end portion (lower-left end
portion in FIG. 3) of the slider 210 on an air exit side
thereof.
[0105] Referring now to FIG. 4, description will be made of a head
gimbal assembly 220 according to this embodiment. The head gimbal
assembly 220 comprises the slider 210, and a suspension 221
elastically supporting the slider 210. The suspension 221 comprises
a load beam 222 in the form of a blade spring made of, for example,
stainless steel, a flexure 223 provided at one end of the load beam
222 and joined with the slider for giving a suitable degree of
freedom to the slider 210, and a base plate 224 provided at the
other end of the load beam 222.
[0106] The base plate 224 is adapted to be attached to an arm 230
of an actuator for moving the slider 210 in the track traverse
direction x of a hard disk 262. The actuator comprises the arm 230
and a voice coil motor for driving the arm 230. In the flexure 223,
a portion where the slider 210 is mounted, is provided with a
gimbal portion for keeping constant a posture of the slider
210.
[0107] The head gimbal assembly 220 is attached to the arm 230 of
the actuator. An assembly in which the head gimbal assembly 220 is
attached to one arm 230 is called a head arm assembly. On the other
hand, an assembly in which a carriage has a plurality of arms and
the head gimbal assembly 220 is attached to each of the arms is
called a head stack assembly.
[0108] FIG. 4 shows one example of the head arm assembly. In this
head arm assembly, the head gimbal assembly 220 is attached to one
end of the arm 230. To the other end of the arm 230 is attached a
coil 231 forming part of the voice coil motor. At an intermediate
portion of the arm 230 is provided a bearing portion 233 that is
mounted on a shaft 234 for pivotally supporting the arm 230.
[0109] Referring now to FIGS. 5 and 6, description will be made of
one example of the head stack assembly and the hard disk drive
according to this embodiment.
[0110] FIG. 5 is an explanatory diagram showing the main part of
the hard disk drive, while FIG. 6 is a plan view of the hard disk
drive.
[0111] A head stack assembly 250 comprises a carriage 251 having a
plurality of arms 252. A plurality of head gimbal assemblies 220
are attached to the arms 252 so as to be adjacent to each other in
the vertical direction with an interval therebetween. A coil 253
forming part of a voice coil motor is attached to the carriage 251
on the opposite side relative to the arms 252. The head stack
assembly 250 is incorporated into the hard disk drive.
[0112] The hard disk drive has a plurality of hard disks 262
mounted on a spindle motor 261. Two sliders 210 are disposed for
each of the hard disks 262 so as to confront each other with the
hard disk 262 interposed therebetween. The voice coil motor has
permanent magnets 263 that are disposed at positions to confront
each other with the coil 253 interposed therebetween.
[0113] The head stack assembly 250 excluding the sliders 210 and
the actuator correspond to a positioning device in the present
invention and serve to support the sliders 210 and to position the
sliders 210 relative to the hard disks 262.
[0114] In the hard disk drive according to this embodiment, the
sliders 210 are moved in the track traverse direction of the hard
disks 262 and positioned relative to the hard disks 262 by the use
of the actuator. The thin film magnetic head included in the slider
210 records information on the hard disk 262 using the recording
head element, while reproduces information recorded on the hard
disk 262 using the reproducing head element.
[0115] The head gimbal assembly and the hard disk drive according
to this embodiment achieve the effect like that achieved by the
thin film magnetic head according to the foregoing embodiment.
[0116] Hereinbelow, a specific example will be shown to describe
the structure of the thin film magnetic head of the present
invention in further detail.
EXAMPLE
[0117] A thin film magnetic head sample as shown in FIGS. 1 and 2
and FIGS. 8 to 17 was prepared.
[0118] A specification of the sample was as follows.
[0119] A substrate 2 of AlTiC, an underlayer of Al.sub.2O.sub.3
having a thickness of 0.3 .mu.m, a lower shield layer of Permalloy
having a thickness of 2.0 .mu.m, a gap of Ta having a thickness of
5 nm, a TMR element (see later description for a detailed stack
structure), a hard magnetic layer (bias layer) of CoCrPt having a
thickness of 23 nm, a gap of Ta having a thickness of 10 nm, an
upper shield layer of Permalloy having a thickness of 1.9 .mu.m, a
separate shield gap layer of Al.sub.2O.sub.3 having a thickness of
0.2 .mu.m, a lower magnetic pole layer of Permalloy having a
thickness of 1.9 .mu.m, and a light gap film of Al.sub.2O.sub.3
having a thickness of 0.1 .mu.m were formed in the order named.
[0120] Further, an upper magnetic layer (pole layer) was formed of
CoFeNi so that the height of an upper pole portion being a tip
portion of the upper magnetic layer became 1.2 .mu.m and the width
thereof became 0.18 .mu.m. An overcoat was formed of alumina so
that the whole thickness thereof became 30 .mu.m.
[0121] The layered structure of the TMR element was as follows.
[0122] Specifically, an antiferromagnetic layer was formed as an
Ir--Mn layer having a thickness of 7 nm, a ferromagnetic layer
(pinned layer) was formed as a Co--Fe layer having a thickness of 4
nm, and a tunnel barrier layer was formed as an Al oxide film. A
ferromagnetic layer (free layer) was formed as a layered film of a
CoFe layer having a thickness of 4 nm and a NiFe layer having a
thickness of 3 nm, which were stacked in the order named from the
tunnel barrier layer side.
[0123] Further, according to the manner shown in the process
diagrams of FIGS. 8 to 17, a heatsink layer was formed at a
rearward portion (in the direction away from the ABS serving as the
recording/reproduction-side surface) of the lower shield layer, the
upper shield layer, and the lower magnetic pole layer for
suppressing introduction of heat generated in the head to the
element side, and a first lead and a second lead were each formed
so as not to have an overlapping portion with the heatsink layer
but to bypass the heatsink layer.
[0124] A junction capacitance C.sub.junction at each of connecting
portions between portions of the element body including the upper
and lower shield layers and the first and second leads was derived
to be 1.04 (pF).
[0125] In this example, since the first lead and the second lead
are each configured so as not to have an overlapping portion with
the heatsink layer as shown, for example, in FIG. 17, (A), a
capacitance.sub.heatsink-lead between the heatsink layer and each
lead is zero. Therefore, the total capacitance was 1.04 (pF).
COMPARATIVE EXAMPLE
[0126] In the manufacture of the foregoing example sample, the
arrangement of the first lead and the second lead was changed.
Specifically, as shown in a plan view of FIG. 18, when drawing
first and second leads 71' and 75', the first and second leads 71'
and 75' were disposed linearly between the extraction electrode
portions and the connecting portions (contact holes) of the shield
layers, respectively, so that each of the first and second leads
71' and 75' had the shortest length. That is, the first lead 71'
and the second lead 75' were each formed so as to have an
overlapping portion with the heatsink layer 40 in a perpendicular
fashion.
[0127] The area of each overlapping portion was derived to be 1000
.mu.m.sup.2 and a capacitance heatsink-lead between the heatsink
layer and the lead at each overlapping portion was 1.11 (pF).
Therefore, the total capacitance was 1.04+1.11=2.15 (pF).
[0128] With respect to the example sample and the comparative
example sample thus prepared, recording/reproducing characteristics
(frequency characteristics) were derived and shown in a graph of
FIG. 7.
[0129] The graph of FIG. 7 shows a relationship between a frequency
(f) and an output (dB) given that an output at frequency f=0 is 0
(dB). The resistance value of the TMR element was 300.OMEGA. and
the capacitance and resistance of a preamplifier were 5 (pF) and
60.OMEGA., respectively.
[0130] From the results shown in the graph of FIG. 7, it is
understood that, in the example sample, since the capacitance of
the reproducing head is reduced from 2.15 (pF) to 1.04 (pF) by
allowing the leads to bypass the heatsink layer to thereby provide
no overlapping portion, the cutoff frequency (frequency at which
the output is reduced by 3 dB) is extended to a higher frequency
side, i.e. from 1.17 (GHz) of the comparative example sample to
1.43 (GHz). The increase contribution rate toward the higher
frequency side is about 22%.
[0131] The effects of the present invention are clear from the
foregoing results.
[0132] Specifically, the present invention is a thin film magnetic
head comprising a read magnetic head element of a CPP (Current
Perpendicular to Plane) structure interposed between a lower shield
layer and an upper shield layer, wherein a heatsink layer is formed
at a rearward portion (in a direction away from an ABS serving as a
recording/reproduction-side surface) of the lower shield layer and
the upper shield layer, and a first extraction electrode portion
and a second extraction electrode portion are formed at a further
rearward portion (in the direction away from the ABS serving as the
recording/reproduction-side surface) of the heatsink layer, and
wherein lead formation patterns of a first lead for connection
between the lower shield layer and the first extraction electrode
portion and a second lead for connection between the upper shield
layer and the second extraction electrode portion are each formed
so as not to have an overlapping portion with the heatsink layer
but to bypass the heatsink layer when observing from the upper
shield layer side toward the lower shield layer in a transparent
state in plan view. Therefore, it is possible to increase an effect
of heat radiation to the substrate side on the basis of the
presence of the heatsink layer to thereby limit propagation of heat
to a magnetoresistive effect layer as much as possible and further
to achieve a drastic improvement in recording and reproducing
characteristics at high recording frequencies, i.e. frequency
characteristics (f characteristics) in a high frequency region.
* * * * *